In a fuel supply device that supplies fuel, which is stored in a fuel tank that receives a sub-tank, to an internal combustion engine located at an outside of the fuel tank, a jet pump has been widely used to pump the fuel from the fuel tank into an inside of the sub-tank. According to the disclosure of JPH11-166460A (corresponding to U.S. Pat. No. 6,098,600A), which discloses one such jet pump, pressurized fuel, which is supplied to a pressurizing passage, is discharged into a diffuser passage through a nozzle passage, so that the fuel, which is stored in the fuel tank, is pumped into the inside of the sub-tank through the diffuser passage.
In the jet pump of JPH11-166460A (corresponding to U.S. Pat. No. 6,098,600A), the nozzle passage includes a communication passage section, is communicated with a downstream end of the pressurizing passage, and a flow restricting passage section, which is communicated with a downstream end of the communication passage section and reduces a flow rate of the fuel in comparison to a flow rate of the fuel at the communication passage section. Here, two passage wall surfaces are opposed to each other while the communication passage section is interposed between the two passage wall surfaces in a width direction that is perpendicular to the flow restricting passage section. Both of these two passage wall surfaces are curved in a form of a concave surface, so that these passage wall surfaces cooperate together to form an arcuate surface, which extends less than 360 degrees in a circumferential direction. With the above-described configuration, the fuel flow, which flows from the pressurizing passage to the communication passage section, is conducted toward the flow restricting passage section located on the downstream side while being swirled along the arcuate surface of the communication passage section. Thereby, the fuel flow is discharged from the flow restricting passage section into the diffuser passage in a state where the fuel flow is swirled. As a result, in the diffuser passage, the fuel flow, which is swirled, forms a liquid fuel film along an entire passage cross-surface area of the diffuser passage. Thus, it is possible to limit a backflow of pumped fuel into the diffuser passage, and thereby the pumping reliability can be improved.
However, in the jet pump of JPH11-166460A (corresponding to U.S. Pat. No. 6,098,600A), the passage width of the pressurizing passage, which is measured in a width direction perpendicular to the extending direction of the flow restricting passage section, is larger than a passage width of the communication passage section, which is measured in the width direction. Thus, a resin portion, which is configured to form the communication passage section of the nozzle passage, needs to be molded by a slide core that is different from a slide core used for molding of a resin portion, which is configured to form the pressurizing passage. In such a case, in order to release the slide core from the resin portion, which forms the communication passage section, after the molding, a portion of the resin portion, which forms the communication passage section, cannot be molded integrally with the resin portion, which forms the pressurizing passage. Thus, an additional manufacturing process of separately molding these resin portions and fixing these resin portions together is required.